As an example of a configuration for connection of an Ethernet frame transmission apparatus to a Wide Area Network (WAN) line, a Wide Area Ethernet network configuration or a synchronous network configuration has been known.
In a Wide Area Ethernet Network configuration, Ethernet frames are directly transmitted over WAN using a L2 transmission apparatus, a L2 switch, or a L3 switch. In a synchronous network configuration, Ethernet frames are transmitted over a synchronous network such as SONET/SDH network.
A bandwidth control device has been proposed which includes a frame retaining unit that retains request frames in the reception frames for requesting data transmission from another processing device, a response measuring unit that measures the size of response frames in reception frames containing data transmitted from another processing device receiving the data transmission request, and calculates, based on the measured size, the predictive traffic volume defined as the size of the traffic of the response frames predicted to be received as a response to the request frames, and a bandwidth control unit that which based on the predictive traffic volume calculated by the response measuring unit, controls traffic rate of the request frames by adjusting timing of transmission of the request frames retained by the frame retaining unit. With this bandwidth control device, it is possible, by calculating predictive traffic volume, to control traffic rate of response frames indirectly by traffic rate control of request frame. Since the size of response frames including requested data is usually larger than the size of the request frames, it is possible with this bandwidth control device to control larger traffic volume with smaller buffer consumption. Also, with this bandwidth control device, with a buffer size comparable to a conventional bandwidth control device, it is possible to deal with far larger number of users and much greater traffic volume while preventing delay or discarding due to congestion.
Related art is disclosed in Japanese Laid-open Patent Publication No. 2008-113117.